Brain Death and Coma: A HealthCentral Explainer

Kyle Glover, the 11-year-old son of R&B singer and actor Usher, has been declared brain dead today after suffering a terrible accident involving a jet ski over the weekend. According to The Press Association, the boy was riding on an inner tube on Lake Lanier in Georgia when he was struck in the head by a passing jet ski.

The cause of the accident is currently under investigation by the Department of Natural Resources in Atlanta, and the district attorney will decide what charges – if any – to file against the jet ski driver once the investigation is complete

Many are confused about the various diagnoses given to people who have suffered head injuries or brain damage, and there has been much controversy over what types of injuries are serious enough to warrant the cessation of life support.

What’s the difference between brain death and a vegetative state?

Brain death is caused by oxygen starvation in the brain. It is also a very specific medical diagnosis that involves the presence of three things: a permanent cessation of brain activity; coma; and apnea, or the lack of the ability for the patient to breathe on his or her own. Once a patient demonstrates these three signs, it’s understood that he or she will never emerge from this state or recover from the injury. Brain dead patients’ hearts may continue to beat – making them technically “alive” – but the removal of life-support equipment will almost certainly lead to death.

This is different from a vegetative state. Vegetative states are a much less certain diagnosis than brain death, and the parameters for its diagnosis are less clear. In a vegetative state, patients have suffered severe brain damage that leaves them in a state of semi-arousal or consciousness. They are not truly conscious or aware in this condition. After four weeks in this state, the patient’s condition is called a persistent vegetative state. After one year like this, the patient is said to be in a permanent vegetative state.

The vast majority of controversial cases involving patients who have life-saving treatments withheld in an attempt to end their lives fall into this latter category. Much of the controversy may stem from the fact that some patients who exist in vegetative states – even for long periods of time – sometimes do simply “wake up” and return to a more normal state.

What about comas?

A coma is an unconscious state that lasts more than six hours in which patients do not respond normally to pain, light, or sound. They cannot be roused from this state, and they do not have a normal sleep cycle or any voluntary movements. Sometimes coma patients may even appear to be awake, lying with their eyes open, but they actually cannot speak, feel, see, or move voluntarily in this condition. The severity of a coma is measured using a measurement tool known as the Glasgow Coma Scale.

Though most people associate coma with head injuries, coma can occur in a wide range of medical conditions, including stroke, intoxication, drug poisoning, cardiac arrest, hypothermia, and hypoglycemia. Sometimes comas are actually purposefully induced in patients who have suffered severe injury to spare them extreme pain during their initial healing from their ordeal.